Well, after all that, letting it idle for an hour, it runs at proper temps, I'm stumped, I would have bet on a blockage somewhere, but like others, I'm leaning to the rad, doesn't have the ability to shed heat. Funny thing, my 36 ford pickup ran an aluminum rad for a few years, cooled fantastic, til the bottom tank split, (epoxy) and I had the stocker recored. My truck runs a 327, all the good parts, flat top pistons, yadda, yadda, anyway, recored the stock rad which is huge dimensionally, with a four core setup, engine takes a long time to come up to 205, when the fan kicks in, sensor is 190, located in the bottom rad tank, guage reads 205, fan turns on, thermostat is 195, takes awhile to come down enough to shut the fan off at 190. Off to the rad shop that built the rad, they tell me that a three core would have been a better choice, four core doesn't dissipate heat easily as a three core or two core rad, seems the back fins don't get the cool air like the front does. However, at speed, the thing cools fantastically, runs 190 even on a 110 degree day. I wish you luck, seems a test with a different rad is in order. By the way, don't let 200 degree temps scare you, all modern engines run 200 all day, it aids in efficiency, I also have a 48 anglia with a 350 in it, 195 thermostat, cools well, won't boil, but definitely don't like crawling along parade routes, she'll run to the boiling point, pretty scary watching that guage, got a tiny rad in it, seems to work though.